<!DOCTYPE HTML>
<html>
<style>
#scrollbox {
  margin: 20px;
  width: 300px;
  height: 400px;
  overflow-y: auto;
  background: -moz-linear-gradient(#444, #555);
}
.opacityBox {
  opacity: 0.999;
  border: 1px solid black;
  margin: 20px;
  padding: 20px;
}
#inner {
  background-image: -moz-linear-gradient(white, rgba(255,255,255,0));
}
</style>

<div id="scrollbox" class="scrollTop">
  <div id="inner">
    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>

    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>

    outside
    <div class="opacityBox">in opacity box</div>
    outside
    <div class="opacityBox">in opacity box</div>
    outside
  </div>
</div>
<script src="scrolling.js"></script>
</body>
</html>
